The day-to-day variation in serum digoxin concentration. The Hørsholm digoxin study.

Serum digoxin concentration was measured in 70 medical patients 7 and 8 days after admission to hospital. The digoxin treatment taken at home was continued in hospital. There was no statistically significant difference between mean digoxin concentrations in samples taken at day 7 (1.52 nmol/l) and day 8 (1.48 nmol/l). The variation in serum digoxin concentration from day to day expressed as SD was 0.25 nmol/l; 95% confidence limits were +/- 0.51 nmol/l, and 99% confidence limits +/- 0.67 nmol/l. Variations in serum digoxin concentration were not correlated to age, sex, body weight, serum creatinine and the oral dose of digoxin.